Conventionally, punch press machines perform punch processing with tools like punches and dies at a fixed punching position, and move the work sheet to the punching position within two axial directions perpendicular to each other. When a work sheet of sheet metal is moved within two axial directions, however, the amount of space the machine takes up is increased. Further, when the work sheet is moved either between front and back or right and left, since the work sheet rubs against either the surface of the work table or free bearings arranged on the table surface, abrasions form easily on the surface of the work sheet.
In order to resolve this problem, a punch press machine which moves the work sheet within only one axial direction (a first axial direction), and whereby a punching position is determined by moving the tools within an axial direction perpendicular to the axial direction in which the work sheet is moved (a second axial direction) has previously been proposed.
Since the punching position in such a punch press machine changes, the punch press machine does not utilize a conventional common turret to hold the tools. Instead, previous punch press machines have stored a plurality of punches and dies in a tower-like tool magazine comprised of multiple levels of peripheral racks arranged behind the machine body from where the desired tool is picked up and moved to the punching position by a tool exchange device.
Such a tower-like tool magazine, however, despite being relatively compact in and of itself, makes efficient utilization of factory floor space difficult, since when added to the tool exchange device behind the body of a punch press machine that is already quite wide, the tool magazine at least partially jutts out. Moreover, the area taken up by the punch press machine including the entire width of the rectangular portion comprising the tool magazine and the body of the punch press machine occupies a lot of floor space.
Furthermore, since the tools that are not in use are stored in the multiple levels of peripheral racks of the tool magazine, retooling operations such as exchanging the tools prepared in the tool magazine and replacement of old tools with new ones is troublesome.